Sensitized photographic emulsion



Patented Apr. 11, 1939 UNITED STATES SENSITIZED PBOTOGBAPHIC EMULSION John David Kendall, more. mums,

Ilford Limited, lliord. Essex, Engla company signer to d, a British Application January 15, 1937, Serial No. 120,789 v In Great Britain May 8, 1985 10 Claims.

This invention consists in improvements in or relating to sensitizing photographic silver halide emulsions.

This application is a continuation-in-part of my copending application Serial No. 77,441, flied May 1, 1936.

The colour sensiti e range of photographic silver halide emulsions hasbeen extended by incorporating in the emulsion many diflerentcom-- pcundadncluding dyestufis of the cyanine and of the-pinaflavol classes. The cyanine dyestufls consist of a heterocyclic nitrogen nucleus, con: taining a quinquevalent nitrogen atom such as that in a quaternary salt, linked to a heterocyclic nitrogen nucleus containing a trivalent nitrogen atom by a'methine or' polymethine chain. The pinaflavol dyestuffs consist of a heterocyclic nucleus containing a quinquevalent nitrogen atom which is linked to a trivalent nitrogen atom by a conjugate chain of carbon atoms part of which is included in a homocyclic ring. In my British specification 'No. 447,109 which corresponds to U. S. Patents 2,080,049 and 2,080,050 I have described the sensitization of photographic silver halide emulsions with dyes similar in structure to the cyanines and pinafiavols, but in which the two nuclei are linked by a. nitrogen atom or by a conjugate chain of nitrogen and carbon atoms. An essential feature of the above-mentioned com- 30 pounds is the presence of a quinqucvalent nitrogen atom linked by a completely conjugate chain .to a trivalent nitrogen atom. It has generally been supposed that it is the presence 0! this systerm which imparts the sensitizing action to the 3 compounds and that compounds which do not contain the system would not possess sensitizing properties.

In British patent specification No. 428,360, however, I have described dyestuffs which do not 40 contain a quinquevalent nitrogen atom and yet possess sensitizing properties. The dyestuffs described in that specification are derived from 5- pyrazolone and I considered that the sensitizing properties were bound up with thepresence of the pyrazolone nucleus in the dyestufl'. Further consideration has now shown that these dyes contain a system comprising two trivalent nitrogen atoms linked by a conjugate chain of an odd number of carbon atoms, and my subsequent investigations have shown that the presence of such a system imparts sensitizing properties to compounds other. than .pyrazalone derivatives. thus I have found that the bases corresponding to the salts employed in the process described in British specification No, 447,109 possess strong sensitizing properties. U

According to the present invention a method of sensitizing photographic silver halide emul sions comprises incorporating in the emulsion an 00 organic nitrogenous base consisting of a heterocyclic nitrogen nucleus linked by a nitrogen atom or by a chain of carbon atoms and at least one nitrogen atom to a second nucleus which is either a heterocyclic nitrogen nucleus'or an amino substituted arylene rin g. a1l the nitrogen atoms in the compound being trivalent and at least two of them being icined by a completely conjugate chain of an odd number of carbon atoms.

The compounds which may be used in accordancewith the present invention are similar in structure to the bases of the cyanine and the pinaflavol types of dyestufl. except that the linking chain consists either of a single nitrogen atom or a. chain of nitrogen and carbon atoms.

The preparation of some of the compounds which may be employed in accordance with the present invention is described in the specification of British Patent No. 447,038 which corresponds to U. 8. Patents 2,080,049 and 2,080,050.

In carrying out the present invention in prace tlce one or more of the compounds to be used in accordance with the present invention may be incorporated in the photographic silver halide emulsion before it is coated on a support, or alternatively the support (e. g. a film or a plate) coated with the emulsion may be bathed in a solution of one or more of the compounds. The actual quantity of the compound incorporated in the emulsion will vary to a certain extent with the individual compounds, and with the ultimate effect which it is desired to obtain. As an indication of the order'oi' the quantities employed 100 cos. of a one in one thousand solution of the dye may be incorporated in six and a half litres of emulsion equivalent to about two hundred and fiity grammes of silver nitrate or the coated support may be bathed in a one in one thousand solution of the compound. The strength of the solution may vary according to the dye used' and may be as low as one in ten thousand.

The following examples'of compoimds which may be used in accordance with the invention are I given by way ofexample only:

(1) 2.2'-dithiazolyl forma'midine extends the sensitivity of a silver chloride photo-- (2') 2.2'-di-p-naphthathialoiyl-I extends the sensitivity of a silver chloride photographic emulsion toebout 5000 A. with a maximum eiiect at about it 4000 L.

(8) 1.1 -di-u-naphthathiuolyl-lormamidine extends the sensitivity of a silver chloride photo:

graphic emulsion to about i 4000 A.

(4) 1:1 dibenztmaeolyl-formasnidine extends the sensitivity or a silver chloride photographic emulsion to about A 4700 A. with a maximum efl'ect at about A 4400 A.

(5) 5:5'-dietho:i:il 1 :1 'dibenzthiazolvl-lormamidine is a powerful sensitize: and extends the sensitivity or a silver chloride emulsion to about i 5000 A with a maximum at about i 4600 A (6) 2- (paradimethvlamino-benzal) -ami1w-pnaphthathiazole s CH , V cm extends the sensitivity oi e sliver chloride photographic emulsion to about it sees it. with a maximum effect at about i 4500 A.

(7) l-(paradimethywmino beam!) -.aminobenzthiazole extends the sensitivity of a silver chloride photographic emulsion to about A 5400 A. with an indeterminate maximum effect at about i 4600 A. This compound is described as 2-para-dimethylamino-benzalaminobenzthiazole in Example V of British patent specification No. 447,038 where its method 01 preparation is given.

(8) S-ethoxy-i-(paradimethylamino benzal) amino benzthiazole CiHlO s LMHQN N// CHI * s s iss ni I I extends the sensitivity of the silver chloride photographic emulsion to about A 5500 A. with a maximum eil'ect at about a 4700 A. s

(9) 1- (N-methuldihfldroquinolylidene-Z) -aminobenzthiazoie 8 =N i l I N/ \N (L1H;

i s powerful sensitizer and extends the sensitivity of silver chloride emulsions to about 7\ 4900 A. with an indeterminate maximum at about 7\ (i0) 1- (N m'ethuldihudrobenzozazolylidene) aminobenzthiazole is a sensitizer and increases the normal sensitivity of a silver chloride emulsion extending the'colour range to about i 4000 A.

with a maximum at about )i 3850 A.

(11) 1 (N methyldihydrobenzthiazolylidene)- aminobenzthiazole is a sensitizer and increases the normal sensitivity of a silver bromide emulsion within its own region and extends the colour sensitivity to about i 4000 A. with a maximum at about i 3850 A.

(12) 1- (N-ethyl-5:6 benzdihudrobenzthiazolylidene) -Gmin0-bnzthiaz0le is a sensitizer and extends the sensitivity of a silver chloride emulsion to about A 4200 A. with a. maximum at about x 3950 A. This compoundmay be prepared from 1-ethylthiol-5z6-benzbenzthiazole etho paratoluene sulphonate and l-aminobenzthiazole in pyridine solution.

(13) 1- (N-methuldihydrobenzthimzolylidene amino-5:6-benzbenzthiazole is a. sensitizer and extends the sensitivity 01' a silver chloride emulsionto about i 4200 A. with a maximum at about i 4000 A. This compound may be prepared from l-methylthiol benzthlazole metho-paratoluene sulphonate and l-aniino-5z6-benzbenzthiazole in pyridine solution.

(14) 1-(1:3'.'3 trimethylindolylidene 2') ethylidene-aminc-benzthiazole CH0 CH5 is a powerful sensitizer and extends the sensitivity of a silver chloride emulsion to )i 5300 A. with a maximum at about a 5000 A. The preparation of this compound is described in Example XV of I claim:

nuclear nitrogenous base compound in which all nitrogen atoms are trivalent, and separated rrom each other by an odd number or carbon atoms, selected from the group consistins oi compounds of the general formula:

Q and compounds otthe general formula:

wherein D and D represent the atoms to complete a heterocycllc nitrogen nucleus taken from the group consisting of member heterocyclic nitrogen ring nuclei the type contained in cyanine dyes, the R's represent a member 01 the group consisting of hydrogen and lower alkyl, A is a trivalent bridging radical selected from the group consisting of =N-CH=N-. ==CKCH=N, and =N-, 13 represents a bivalent bridging radical of the formula --N==CH'-, and X represents a phenylene radical.

2. A photographic silver halide emulsion containing in sensitizing amounts an organic binuclear nitrogenous base compound in which on nitrogen atoms are trivalent and having the gen eral formula:

wherein D and D represent the atoms necessary to complete a heterocyclic nitrogen nucleus taken.

from the group consisting oi B-member and 6- member heterocyclic nitrogen ring nuclei of the type contained in cyanine dyes, R is a member of the group consisting of hydrogen and lower alykyl and A is a trivalent bridging radical selected from the group consisting of b -member and 6- wherein D and D" represent the atoms necessary A to complete a heterocyclic nitrogennucleus taken from the group consisting of li-member and 6- member heterocyclic nitrogen ring nuclei of the type contained in cyanine dyes.

4.'A sensitized photographic silver halide emulsloli which has incorporated in it as the sensitlser i:1'-dlbenz-thiasolyl1ormamidine.

5. A sensitized photographic silver halide emulsion which has incorporated in it as the sensitiser a dithlazolyltormamidine.

6, A photographic silver halide emulsion con taining in sensitizing amounts. an organic binuclear nitrogenous base compound in which all nitrogen atoms are trivalent and having the general formula:

wherein D and D represent the atoms necessary to complete a heterocycli'c nitrogen nucleus taken from the group consisting o1 5-member and 6- and having the general formula:

wherein D represents the atoms necessary to complete a heterocyclic nitrogen nucleus taken ,from the group consisting of S-member and 6- 4 benzthiazole.

JOHN nsvm month.

Patent No. 2,153,930.

Certificate of Correction JOHN D and that the said Letters Patent should b April 11, 1939c. AVID KENDALL It is hereby certified that error a numbered patent re in the formula, for

ppears in the printed specification of the ztbove quiring correction as follows: Page 2 first column, lines 2 to 9,

. read 9 e read with this correction. therein that the same may conform to the record of the case in the Patent Signed and sealed this 25th day of dimly, A. 1D; 1989;.-

[SEAL] VET Aiding Commiseiom of l atewfie, 

